ONIX display - other values - Editions types in ONIX list 21

[chrisONIX]

In the User Experience Guide for Displaying Accessibility Metadata - general information section - add a general reference to special edition types that are included in ONIX code list 21 - https://ns.editeur.org/onix/en/21 . These are aimed at everyone but some do have accessibility features. The ones that could be mentioned are: BRL - Braille edition ETR - Easy-to-read edition HRE - High readability edition LTE - Large type / large print edition ULP - Ultra large print edition